After having my car for almost 7 years, 3 of which with a supercharger, I FINALLY swapped out the gears! The stock LSD was also starting to give some trouble locking up. So out go the 3.27s and in go the 3.73s.

First thoughts: wow, what a difference! The lag from a dig with the stock converter is nearly gone. 2nd gear pulls onto a highway are much more fun. 3rd gear (1:1) pulls with the converter locked are freakin' awesome. And ironically, the first several tanks of gas I have gotten BETTER gas mileage. Albeit they are both entirely city driving, it went from around 15-16 average to over 18 on both of them. Best city mileage I've ever gotten.

I also did the swap myself. I was a little worried at first, but it was actually really easy. The only special tools needed are a dial indicator/mount, a hydraulic press, and some way to get the bearing races out (I just used a brass punch and brute force). I had no real snags on the entire install. I was able to get backlash to .0135" (recommended is .012-.015), which is pretty much perfect. Teeth contact pattern looked perfect, too. So far, I've got nearly 1000 miles on them, and they are quieter than the stock gears. I used full synthetic Mobile 1 75w140 oil with one bottle of Ford friction modifier.

I also went ahead and installed 31 spline axles at the same time. I shopped around for a while, and got great deals on all of the parts (all new). In the entire build (FRPP gears, Ford bearings/install kit, new 31 spline T-lok, new Superior 31 spline axles, Superior wheel studs, oil), I've got right at $600 in everything. Not bad at all for all new parts on a 31 spline upgrade.

Also, big shout-out to Tousley Ford. If you ever need any FRPP parts, check them out. I got FRPP gears for $130 shipped, and the good install kit (GT500 bearings, better gasket, etc.) for $90. They've also got 31 spline differentials at a good price.

If it was purely a street car, or purely a track car, I probably would have. After driving my granddad's Mach with 4.10s, they are definitely a lot of fun at [mostly] legal speed on the street, and would work nicely at the track with some 28" tires. But since I run at the track on a shorter, stock height tire, I had to go 3.73. 4.10s at 6200 rpm only get 115 mph; I'm trapping upper teens, so that'd mean I'm over 6000 rpm for at least a couple seconds, up to almost 6500, on a given run, and I didn't want to do that.

3.73s get me 122 mph at 6000 rpm, so that's almost perfect. It will be perfect when I get done with the next few things on the car.

Nah, did it all under the car. I jacked it up off the ground a good couple of feet. It wasn't that bad at all; I just about could sit up underneath it. The only aggravating thing to do under the car was beating the pinion bearing races in and out, and tightening the pinion nut. But even then, they weren't really that bad.

As I mentioned earlier, the swap really was a lot easier than I thought it would be. If you have a lift, the right tools, and the know-how, this could easily be done in a few hours. A simple gear swap could probably be done in two. Shops definitely make a nice penny on doing these swaps for people.

I am glad it worked out for you. I would love 3.73s in my 02. I would have to lose the kenne bell tune and get a custom one I imagine. The car might actually launch pretty good wih the upr upper and lower control arms and torque box reinforments. I can't wait for your next video.

If it was purely a street car, or purely a track car, I probably would have. After driving my granddad's Mach with 4.10s, they are definitely a lot of fun at [mostly] legal speed on the street, and would work nicely at the track with some 28" tires. But since I run at the track on a shorter, stock height tire, I had to go 3.73. 4.10s at 6200 rpm only get 115 mph; I'm trapping upper teens, so that'd mean I'm over 6000 rpm for at least a couple seconds, up to almost 6500, on a given run, and I didn't want to do that.

3.73s get me 122 mph at 6000 rpm, so that's almost perfect. It will be perfect when I get done with the next few things on the car.

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That is why I switched from 4.10's to 3.73's, I was going thru the traps bouncing off my 6k rev limiter.